A PVC liner is inserted into a watermain between two manholes. Hot steam is then used to expand the liner to the width of pipe. The thermosetting resin in the liner is then cured by the steam and hardens. After cooling, the liner is now waterproof. This trenchless technology is used to stop leaks from imperfections or gaps in piping.
Ok, in reality it sits in the paint booth at the new TTC Leslie Streetcar Barns during Doors Open Toronto 2016.
The highway is closed this weekend for annual Spring maintenance.